Definition 3.6 [1]}
A tensor \(\mathcal {A}= (a_{i_1 i_2 ... i_m}) \in T_{m,n} \)  is said to be \(Z\) -tensor if all its off-diagonal entries are nonpositive, i.e. \(a_{i_1...i_m} \le 0\)  when \(\delta _{i_1...i_m} =0 .\)

